Topic 2:

Fibrosis Imaging: It DOES Matter if You are Black or White!

 Speaker: Dr Calvin Chin

The pathogenesis of myocardial fibrosis is complex and the distribution varies depending on the underlying etiology, although it generally exists in two predominant forms: Replacement fibrosis commonly occurs late in the disease process, is not believed to be reversible and is characterised by a more localised distribution corresponding to areas of myocyte loss. By contrast, interstitial fibrosis is more diffusely distributed, reflecting a more uniform and progressive accumulation of collagen in the interstitium, and is believed to be reversible with targeted therapies. Myocardial biopsy is the gold standard of diagnosing myocardial fibrosis. However, it is invasive, susceptible to sampling errors and unable to assess the fibrotic burden of the whole heart. Non-invasive imaging techniques have been developed to assess myocardial fibrosis. In particular, the use of gadolinium contrast in cardiovascular magnetic resonance has dramatically improved tissue characterisation. In late gadolinium enhanced imaging, focal regions of fibrosis appears bright relative to surrounding darker appearing normal myocardium. However, this technique relies on a difference in signal intensity between normal and fibrotic regions and therefore, may not accurately reflect the more diffuse pattern of fibrosis that predominates in some cardiac conditions. More sensitive myocardial T1 mapping techniques have been developed to quantify fibrosis in the myocardium. Recent data have demonstrated an important prognostic association between T1 mapping and patient outcomes, underscoring diffuse myocardial fibrosis as a latent phenotype conferring vulnerability.

Cardiac MRI in Acute Myocardial Infarction: The Harder You Look the More You See!

 Speaker: Prof Derek Hausenloy 

Acute coronary syndromes (ACS) are a leading cause of death and disability in Singapore and worldwide. As such new treatments are required to improve clinical outcomes in patients with ACS. In this regard, cardiac magnetic resonance imaging (MRI) imaging has the unique ability to tissue characterise the myocardium in patients presenting with an ACS. This can allow the direct visualisation and quantification of microvascular obstruction, intramyocardial haemorrhage, acute myocardial infarct size, myocardial salvage, interstitial fibrosis in the remote myocardium, all of which are surrogate clinical endpoints and predictors of clinical outcome post-ACS. Cardiac MRI can therefore provide new insights into the pathophysiology underlying an ACS and can be used to assess the cardioprotective efficacy of new treatments for improving clinical outcomes in ACS patients.

Topic 4:

Novel Method of Assessing Heart Contractile Function: The Crux of the Matter

 Speaker: Assoc Prof Tan Ru San

Diverse heart imaging modalities are used to assess global and regional myocardial function to aid in heart failure (HF) diagnosis: echo, nuclear emission computed tomography and cardiac magnetic resonance (CMR). Of these, CMR arguably provides superior resolution and reproducible results of ventricular ejection fractions and volumes. Current CMR techniques fail to exploit the full potential of the rich image dataset. We previously demonstrated ventricular curvedness and curvedness rate imaging as novel and promising clinical approaches for assessment of global and regional myocardial left ventricular (LV) function in HF. From CMR, we segmented and reconstructed 4D computational heart models to calculate local regional LV curvedness, surface area strain and wall stress.

We believe analysis of global and regional myocardial function can facilitate robust evaluation of HF, extending CMR’s diagnostic potential spatiotemporally by analysis of morphological and topological information throughout all phases of the cardiac cycle. Local LV point curvedness is independent of spatial reference and thus computationally efficient. We have developed rapid computational algorithms for calculation of LV curvedness and its derivatives. We believe that automated method for rapid comprehensive assessment of systolic and diastolic LV functional performance that is physiologically meaningful and reproducible shall answer an unmet clinical need.

*Information is correct at time of update